1. Technical Field
The present invention relates to a transport apparatus which prevents slack of a recording medium in a roll shape during its transport, a printer including the transport apparatus, and a method of loading a recording medium onto the printer.
2. Background Art
In a printer for performing printing on a recording medium in a roll shape, the recording medium fed from a feeding roll is wound up onto a take-up roll after the printing is performed in a printing area. To perform desired printing using such a printer, an appropriate tension, that is, a tensile force, needs to be applied continuously to the recording medium so that the recording medium passes through a predetermined position of the printing area precisely. To apply the tension, there is employed a method in which a tension bar having a weight corresponding to a desired tension is placed on a slack portion of the recording medium to eliminate the slack of the recording medium due to the weight of the tension bar itself.
In the conventional printer, however, the tension bar is simply placed on the recording medium, and hence, when the recording medium is transported in an abnormal manner such as meandering, a large force is applied to the recording medium so that the tension bar may vibrate along with the recording medium. This case leads to a problem in that the tension which the tension bar may apply to the recording medium fluctuates. Therefore, the recording medium cannot be aligned at the predetermined position of the printing area, and further wrinkles caused in the recording medium extend in a transport direction, which hinders the desired printing. In addition, when the vibration of the tension bar is large, there may further arise problems of secondary vibration and damage to the recording medium.
Further, when the tension bar is placed on the recording medium, the tension can be applied in the transport direction of the recording medium but cannot sufficiently be applied in a width direction of the recording medium. Hence, warp of the recording medium cannot be suppressed. Further, movement of the recording medium in the width direction cannot be regulated, and hence skewing of the recording medium cannot be suppressed. The warp and skewing may hinder the printed recording medium from being wound up regularly.
To address this, in the apparatus described in Patent Literature 1, that is, JP 2005-154142 A, the tension bar includes pinions at both end portions thereof in a shaft direction, and the pinions mesh with racks provided on the apparatus side, respectively. With this structure, even if a force is applied to the recording medium due to a disturbance or the like, the same height can be maintained at both the ends of the tension bar on the right and left.